156 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



rapid succession of waves of small amplitude passing along the flagellum 

 from the base to the top. The smaller food particles are captured by 

 choanocytes and passed on to the amoebocytes ; the coarse ones stick in 

 or against the prosopyles, and are taken into the adjacent thin layer of 

 apparently undifferentiated fluent protoplasm. Defecation (and perhaps 

 excretion) takes place by means of vacuoles in amoeboid cells along the 

 walls of the excurrent canals, and it may be on the surface as well. 

 The mesogloea is not undifferentiated plasma ; it consists entirely of 

 amoeboid cells. J. A. T. 



Protozoa. 



Axial Rotation of Aquatic Micro-organisms. — L. B. "Walton 

 (Amer. Naturalist, 1918, 52, 521-46, 5 figs.). In the progressive swim- 

 ming movement of most aquatic micro-organisms there is a characteristic 

 axial rotation. Jennings has called attention to the value that such a 



Urceolus costatus. 



Heteronema spirale. 



Flagellate forms from the Northern Hemisphere, illustrating the 

 development of the left-hand striae. 



compensatory motion may have for the organism in which it exists. 

 "Walton points out that an oblique striation forward and to the left is in 

 Flagellates from the Northern Hemisphere associated with an axial 

 rotation from right over to left, so-called " clock-wise." Forms with a 

 reverse striation seem to be absent from the Northern Hemisphere, 

 although such forms occurred in the Southern Hemisphere. As Eugle- 

 noids and the like are in general positively phototactic the rotation may 



